Information equipment with polymer film in bearing and disk

ABSTRACT

A rolling bearing is used for supporting a rocking mechanism or a rotating mechanism, and a film comprising a fluorine-containing polymer having a functional group(s) under a fluidizied state or a film comprising a fluorine-containing polyurethane compound under a solid state is formed on at least the track surface of the rolling bearing. Since this film does not contain ions for uniformly dispersing a thickner having non uniform particle sizes such as fluorine based grease of the prior art, breakage of the film between a rolling element and a race is not likely to occur, and wear of a rolling element race resulting from the direct contact between them due to breakage of the film can be reduced. When this film is tha same kind of a film as a protective film of the surface of an information recording disk, dust generating components of the film are the same kind of components as those of the protective film, and information recording/reproduction of the information recording disk is not impeded.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/JP98/01270 which has an Internationalfiling date of Mar. 24, 1998, which designated the United States ofAmerica.

TECHNICAL FIELD

The present invention relates to an information equipment. Specifically,the information equipment includes a drive device of a disk forrecording information, such as a magnetic disk, an optical disk and thelike, for example, a hard disk drive (HDD) device.

BACKGROUND ART

While the information equipment includes a rotating mechanism, such as aspindle fixed as piercing at the rotating center of a disk for recordinginformation, and a rocking mechanism, such as a swing arm for moving ahead for recording/reproduction of information, a spindle of a rockingfulcrum in the swing arm as the rocking mechanism is supported by tworadial rolling bearings, as described, for example, in JP-A-5-135515. Inthe rolling bearing, a fluorine based grease excellent in lubricatingproperty is used as a lubricating agent, and the minimum necessaryamount thereof is sealed. As the fluorine based grease, one to whichfine powder (for example, having a particle diameter of from 2 to 3 μm)of PTFE (polytetrafluoroethylene) or the like is added, such as a PTFEfluorocarbon oil grease, PTFE fluorosilicone oil grease, PTFEfluorinated polyether oil grease and the like, is exemplified. Thefluorine based grease of this type employs an appropriate amount of anion to make uniform the dispersion of a thickener having a non-uniformparticle size.

In the information equipment, among the rotation mechanism and therocking mechanism, the fluorine based grease described above is employedin a rolling bearing used for supporting a swing arm as the rockingmechanism, for example, and thus the problems described below occur.

Firstly, because the swing arm exhibits a movement of repeatedly rockingwithin a prescribed range of angle, the rolling element is sometimesdragged to slip at the rolling spindle that supports it, and at thistime, in the case where a fluorine based grease is used as thelubricating agent described above, breakage of the film is likely tooccur between the rolling element and a race. Such breakage of the filmmay become a cause of occurrence of wear of the rolling element and therace -due to direct contact of the rolling element and the race.

Furthermore, in the case of the PTFE as a thickener added to thefluorine based grease, a particle diameter larger than the standard aremixed due to difficulty in selecting a operation. Also, a minute spikenoise is generated from the rolling spindle, and the torquecharacteristics for the rocking movement of the swing arm is likely tobecome unstable, which becomes a cause of lowering of the positioningaccuracy of a head on the recording/reproduction.

Furthermore, leakage of the fluorine based grease may occur, and in thecase where the ion for uniform dispersion of the thickener, inparticular, of the leaking fluorine based grease is attached to thesurface of the disk for recording information to be incorporated into aprotective film of the disk for information recording, a problem occursin that it becomes an obstruction of recording/reproduction.

Furthermore, in the case where such an information equipment is used ina low pressure atmosphere, such as under vacuum, a gas is generated fromthe fluorine based grease, and a problem occurs in that the gasadversely affects the protective film of the disk for recordinginformation.

Furthermore, in the case of a grease other than the fluorine based one,a problem occurs in that a hydrocarbon contained therein adverselyaffects the information equipment. Furthermore, in a bearing using agrease, when it is not used but allowed to stand for a long period oftime, the grease is hardened to cause a problem in that the rotationtorque at the beginning of use becomes large.

Therefore, an object of the invention is that in an informationequipment, the lubricating property, the torque characteristics and theproperty of generation of dusts of a rolling bearing for supporting arocking mechanism or a rotating mechanism are improved, so as tostabilize the operation of the recording/reproduction of information.

DISCLOSURE OF THE INVENTION

[Constitution]

(1) A first information equipment embodiment of the invention comprisesa rocking mechanism for rocking an element of the equipment, and arolling bearing for supporting the rocking mechanism, wherein therolling bearing has, on at least a race surface thereof, a filmcomprising a fluorine-containing polymer having a functional groupformed under a state having fluidity, and a thickness thereof is set at0.2 μm or less.

In the first embodiment of the invention, preferably, the rollingbearing has the film formed at least one race surfaces of an inner raceand an outer race.

In the first embodiment of the invention, preferably, the functionalgroup has high affinity to a metal.

In the first embodiment of the invention, preferably, thefluorine-containing polymer is a fluoropolyether polymer.

In the first embodiment of the invention, preferably, thefluorine-containing polymer is a polyfluoroalkyl polymer.

In the first embodiment of the invention, preferably,recording/reproduction of information is conducted to a disk forrecording information having, on a surface thereof, a protective film ofthe same component as the film.

(2) A second information equipment embodiment of the invention comprisesa rotating mechanism for rotating an element of the equipment, and arolling bearing for supporting the rotating mechanism, wherein therolling bearing has, on at least a race surface thereof, a filmcomprising a fluorine-containing polymer having a functional groupformed under a state having fluidity, and a thickness thereof is set at0.2 μm or less.

(3) A third information equipment embodiment of the invention comprisesa rocking mechanism for rocking an element of the equipment, and arolling bearing for supporting the rocking mechanism, wherein therolling bearing has, on at least a race surface thereof, a solid filmcomprising a fluorine-containing polyurethane polymer compound.

In the third embodiment of the invention, preferably, the rollingbearing has the film formed at least one race surfaces of an inner raceand an outer race.

In the third embodiment of the invention, preferably, thefluorine-containing polyurethane polymer compound has athree-dimensional network structure.

In the third embodiment of the invention, preferably, afluorine-containing polymer compound having fluidity is added to thefluorine-containing polyurethane polymer.

In the third embodiment of the invention, preferably,recording/reproduction of information is conducted to a disk forrecording information having on a surface thereof, a protective film ofthe same component as the film.

(4) A fourth information equipment embodiment of the invention comprisesa rotating mechanism for rotating an element of the equipment, and arolling bearing for supporting the rotating mechanism, wherein therolling bearing has, on at least a race surface thereof, a solid filmcomprising a fluorine-containing polyurethane polymer compound.

(5) A fifth information equipment embodiment of the invention comprisesa head for recording/reproduction for conducting recording/reproductionof information to a disk for recording information, a rocking mechanismfor moving the head by rocking, and a rolling bearing for supporting therocking mechanism, wherein the rolling bearing has, on at least on arace surface thereof, a film of the same kind as a protective film on asurface of the disk for recording information, formed under a solidstate, and the film comprises a fluorine-containing polyurethane polymercompound.

[Function]

The film according to the invention, the functional group of thefluorine-containing polymer or the three-dimensional network structureof the fluorine-containing polyurethane polymer compound is firmlyadhered to the adherend surface, whereby breakage of the film andgeneration of dusts are difficult to occur, and the friction resistanceis extremely small. Furthermore, the film does not contain the thickenerhaving a non-uniform particle diameter or the ion for uniform dispersionof the thickener as in the conventional fluorine based grease. Moreover,when the film thickness of the film is set as thin as possible at 0.2 μmor less, generation of dusts of the oily component will substantiallynot occur. Therefore, the operation of the rolling bearing becomesextremely smooth, and minute spike noise that occurs conventionally arenot generated.

[Effect]

Accordingly, the information equipment of the invention becomesextremely smooth, and the torque characteristics stabilized, forexample, a minute spike noise that occurs conventionally is notgenerated because a film that is difficult to obtain breakage orgeneration of dusts, exhibits an extremely small friction resistance.Further, because the information equipment of the invention does notcontain the thickener having a non-uniform particle diameter or the ionfor uniform dispersion of the thickener as in the conventional fluorinebased grease that controls the thickness thereof, on a race surface of arace of a rolling bearing used in a rocking mechanism or a rotatingmechanism thereof.

In the case where the information equipment of the invention comprises adisk for recording information and a head for recording/reproductionprovided in the vicinity of the rolling bearing, the positional accuracyof the head for recording/reproduction and the rotating accuracy of thedisk for recording information are improved because the torquecharacteristic of the rolling bearing for their fulcrum is stable.Moreover, even though a dust component from the film is incorporated ina protective film which is generally formed on the disk for recordinginformation, it is not an obstruction of the recording/reproductionbecause the film is of the same component as the protective film.

As described herein, the invention can provide an information equipmenthaving high reliability that exhibits an excellent performance for along period of time.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a vertical sectional view of a hard disk drive deviceaccording to one embodiment of the invention;

FIG. 2 is an enlarged diagram of a half of a rolling bearing of a movingunit of FIG. 1;

FIG. 3 is a schematic constitutional view of a test equipment used underan atmospheric environment;

FIG. 4 is a schematic constitutional view of a test equipment used undera vacuum environment;

FIG. 5 is a graph showing measurement results of the ion contaminationperformance;

FIG. 6 is a graph showing measurement results of the out gasperformance;

FIG. 7 is a graph showing test results of the torque life of the bearingunder an atmospheric environment;

FIG. 8 is a graph showing measurement results of change in torque afterallowing stand at ordinary temperature;

FIG. 9 is a structural diagram schematically showing the structure ofthe film formed in the rolling bearing of FIG. 2;

FIG. 10 is a graph showing results of characteristics analysis of thefilm in the state before hardening;

FIG. 11 is a graph showing results of characteristics analysis of thefilm in the state after hardening; and

FIG. 12 is a graph showing test results relating to the torque life ofthe bearing under a vacuum environment.

BEST MODE FOR CARRYING OUT THE INVENTION

The invention will be described in detail below based on the best modefor carrying out the invention shown in the attached drawings.

The elements constituting the hard disk drive device as the informationequipment shown in FIG. 1 is described, in which numeral 1 denotes aframe of the hard disk drive device, 2 denotes a disk for recordinginformation, such as a magnetic disk, an optical disk and the like,arranged horizontally inside the frame 1, 3 denotes a spindle unitsupporting the disk 2 for recording information freely rotatable to theframe 1, 4 denotes a recording/reproduction head conductingrecording/reproduction to the disk 2, and 5 denotes a movement unit formoving the recording/reproduction head 4 to an arbitrary track of thedisk 2 for recording information.

A protective film (not shown in the figure) is formed on the surface ofthe disk 2 for recording information in under a state having fluidity.The protective film generally comprises perfluoropolyether (PFPE).

The spindle unit 3 comprises a spindle 6 fixed as piercing at therotating center of the disk 2 for recording information under a state ofprotruding upward and downward, rolling bearings 7 supporting the partsof the spindle 6 protruding upward and downward freely rotatable withrespect to the frame 1, and a motor 8 for rotatably driving the disk 2for recording information.

In the invention, the spindle 6 supported by the rolling bearings 7forms the rotating mechanism, but the rotating mechanism is not limitedthereto, and any rotating mechanism among the mechanism elementscontained inside the information equipment is included therein.

The motor 8 comprises a rotor 9 comprising a permanent magnet fixed atthe lower end of the spindle 6 protruding downward with respect to theframe 1, and a stator 10 comprising a coil oppositely aligned at thelower portion of the rotor 9 in a non-contact state.

The stator 10 is adhered to a yoke 13 attached on a substrate 11 on theside of the frame 1 through an elastic body 12 such as a coil springrepulsing and energizing.

The movement unit 5 comprises a swing arm 14 to which therecording/reproduction head 4 is attached, a head carriage axis 15 fixedto the frame 1, a pair of rolling bearings 16 supporting the swing arm14 by the head carriage axis 15 freely rockable, and a motor 17 drivingrockably the swing arm 14.

In the invention, the swing arm 14 and the head carriage axis 15, as therocking mechanism, are supported by the rolling bearings 16, but therocking mechanism of the invention is not limited thereto, and anyrocking mechanism among the mechanism elements contained inside theinformation equipment is included therein.

The motor 17 comprises a rotor 18 comprising a permanent magnet fixed atthe lower end of the swing arm 14, and a stator 19 comprising a coilarranged facing and under the rotor 18 in a non-contact manner.

The stator 19 adhered to a yoke 21 attached to the substrate 11 on theside of the frame 1 through an elastic body 20 such as a coil repulsingand energizing.

The pair of rolling bearing 16 provided in the movement unit 5 is a deepgroove ball bearing comprising an inner race 22, an outer race 23, aspherical rotating body 24, a retainer in a crown shape 25 and a seal26.

The inner and outer races 22 and 23, and the rotating body 24 are formedwith a metallic material.

As the metallic material, for example, a high carbon chromium bearingsteel such as SUJ2 of the JIS can be exemplified. In the case wherecorrosion resistance is demanded, a metallic material obtained byconducting a suitable hardening heat treatment to a martensite seriesstainless steel such as SUS440C of the JIS, a deposition hardening typestainless steel such as SUS630 of the JIS, and the like are preferred.In the usage of a light load, an austenite series stainless steel suchas SUS304 of the JIS may be used. The rotating body 24 may be formedwith a ceramic material. As the ceramic material, those mainlycomprising silicon nitride (Si₃N₄) with using, as a sintering aid,yttria (Y₂O₃) and alumina (Al₂O₃), as well as aluminum nitride (AlN),titanium oxide (TiO₂) and spinel (MgAl₂O₄), as well as those mainlycomprising alumina (Al₂O₃), silicon carbide (SiC), zirconia (ZrO₂),aluminum nitride (AlN) and the like may be used.

The retainer 25 is formed with a soft steel such as an SPCC material, aswell as a synthetic resin material.

As the synthetic resin material, a general polyamide resin (nylon 66),as well as a thermoplastic resin having heat resistance, for example, afluorine based resin, such as polytetrafluoroethylene (hereinafterabbreviated to PTFE), ethylene tetrafluoroethylene (ETFE) and the like,engineering plastics, such as polyetheretherketone (PEEK),polyphenylenesulfide (PPS), polyethersulfone (PES), nylon 46 and thelike, and the like may be used. As the type of the retainer, in additionto the crown shape shown in the figure, a wave shape, a rice hull shapeand the like may be arbitrarily used.

In the invention, a film 27 comprising a fluorine-containing polymercontaining a functional group or a film 27 in a solid state comprising afluorine-containing polyurethane polymer compound is formed on the outerperipheral surface of the inner race 22, the inner peripheral surface ofthe outer race 23, the surface of the rotating body 24, and the surfaceof the retainer 25.

The case (A) where the film 27 comprising the fluorine-containingpolymer is formed, and the case (B) where the film 27 comprising thefluorine-containing polyurethane polymer compound is formed aredescribed separately in detail below.

(A) Film 27 Comprising Fluorine-containing Polymer Having FunctionalGroup

In the case of the film 27 comprising the fluorine-containing polymerhaving a functional group, it is formed on the outer peripheral surfaceof the inner race 22, the inner peripheral surface of the outer race 23,the surface of the rotating body 24, and the surface of the retainer 25under a state having fluidity. The film 27 may be formed at least on therace surfaces of the inner and outer races 22 and 23.

The film 27 has the same component as the protective film of the disk 2for recording information as described in the foregoing. As thefluorine-containing polymer, a fluoropolyether polymer or apolyfluoroalkyl polymer is preferred.

As the fluoropolyether polymer, those having a unit shown by the generalformula —C_(x)F_(2x)—O— (X is an integer of from 1 to 4) as the mainstructural unit, and having a number average molecular weight of from1,000 to 50,000 are exemplified.

As the polyfluoroalkyl polymer, those shown by the following chemicalformula 1 are exemplified.

As the functional group, those having high affinity to a metal (forexample, an alcohol group, an epoxy group, an amino group, a carboxylgroup, a hydroxyl group, a mercapto group, an isocyanate group, asulfone group, an ester group or the like) are preferred.Polyfluoroalkyl polymers having such a functional group are shown by thefollowing chemical formulae 2 and 3. These fluorine-containing polymersmay be used singly or may be used in combination of two or more kinds.In this case, in order to obtain a thin film that is further excellentin wear resistance, it is desirable that consideration is made in thatthe groups combined react each other to make the polymer to have afurther high molecular weight.

As the film 27 described above in more detail, a perfluoropolyether(PFPE) or a mixture with a derivative thereof, specifically FONBLIN YStandard, FONBLIN Emulsion (FE20, EM04 and the like) and FONBLIN Zderivatives (FONBLIN Z DEAL, FONBLIN Z DIAC, FONBLIN Z DISOC, FONBLIN ZDOL, FONBLIN Z DOLTX2000, and FONBLIN Z TETRAOL, etc.), trade names, ofMontecatini Inc., is preferably used. Those exemplified have a highconcentration and are extremely poor in affinity to a metal, and theyare difficult to be attached in the form of a film as they are.Therefore, the following method is applied to the formation of the film27.

An example of a method for forming the film 27 described above is thendescribed below.

(A-a) Attaching Treatment

A solution for obtaining the film 27 comprising the fluorine-containingpolymer having a functional group is prepared, and the inner and outerraces 22 and 23, the rotating body 24 and the retainer 25 areindividually immersed in the solution, or the bearing 16 in the stateobtained by fabricating them is immersed and rotating in a few times, soas to attach a film in a liquid state to the inner race 22, the outerrace 23, the rotating body 24 and the retainer 25.

In the case of locally attaching, it is immersed after masking theunnecessary part, or the solution is sprayed. Furthermore, the solutionmay be injected in the position between the inner and outer races 22 and23, at which the rotating body 24 is present, by a syringe that caninject the solution in a slight amount. The solution prepared herein isobtained by diluting, for example, FONBLIN Z DOL2000 (the molecularweight is 2,000) of FONBLIN Z DOL with a suitable dilution solvent(fluorine series solvent SV90) to a FONBLIN concentration of from 0.25to 1.0 mass %.

(A-b) Drying Treatment

The whole of the rolling bearing 16, to which the liquid state film isattached, is heated to from 40 to 50° C. for about 3 minutes to removethe solvent contained in the liquid state film.

(A-c) Finishing Drying Treatment

Thereafter, considering the atmospheric temperature of the environmentwhere the bearing is used, it is heated to, for example, from 80 to 180°C. for from 15 to 60 minutes.

The attaching treatment (A-a) and the drying treatment (A-b) may berepeated several times depending on necessity, and finally the filmthickness of the film 27 is set at, for example, 0.2 μm or less.However, the property of the solution used, the method for forming thethin film, the film thickness after formation and the like may beappropriately set.

According to the procedures, in the constitutional elements of therolling bearing 16, the film 27 can be formed at the parts that are incontact with each other to a suitable thickness, and by removing thesolvent as described above, unnecessary generation of dusts on operationof the rolling bearing 16 does not occur. Since the film thickness ofthe film 27 is set at extremely thin, generation of dusts due to an oilycomponent does substantially not occur.

Because the functional group of the fluorine-containing polymer isfirmly fixed to the adherend surface (the surface of the rollingbearing), the film 27 is difficult to suffer breakage of the film andgeneration of dusts, and exhibits extremely small friction resistancealthough it has fluidity. Furthermore, the film 27 has the samecomponent as the protective film (not shown in the figure) attached tothe disk 2 for recording information, and does not contain a thickenerhaving non-uniform particle diameters or an ion for uniform dispersionof the thickener, as in the conventional fluorine based grease.

Accordingly, the torque characteristics is stabilized, for example, theoperation of the rolling bearing 16 for supporting therecording/reproduction head 4 becomes extremely smooth, so as not toform a minute spike noise, which has been conventionally observed, andas a result, the positional accuracy of the recording/reproduction head4 is improved. Even when the dust component generated from the film 27is caught by the protective film of the disk 2 for recordinginformation, because the protective film and the dust component from thefilm 27 have the same component, it does not become obstruction ofrecording/reproduction.

The dust generation life and the torque life of the film 27 describedabove have been investigated, and are described. Two samples, an exampleand a comparative example, are investigated herein.

In Example A, the film 27 is formed on the whole surfaces of the innerand outer races 22 and 23, the rotating body 24, and the retainer 25,and the thickness thereof is set at 0.2 μm. As the film 27, afluorine-containing polymer having a functional group with an end groupof a hydroxyl group (—OH) (FONBLIN Z Derivative (FONBLIN Z DOL2000)) isused, with the concentration being 0.25 mass % and the film thicknessbeing 0.2 μm.

In Comparative Example A, DEMNUM, a trade name, produced by DaikinIndustries, Ltd. is used as a fluorine based grease, which is sealed inthe rolling bearing 16.

For the test in an atmospheric environment, the equipment shown in FIG.3 is used, and for the test in a vacuum environment, the equipment shownin FIG. 4 is used. In the figures, numerals 50 and 50 denote testbearings, 51 denotes a rotation axis, 52 denotes a casing, 53 denotes amagnetic fluid seal, 54 denotes a device for measuring the number ofdusts generated (a particle counter), 55 denotes a device for recordingthe measurement results (a recorder), 56 denotes a bearing housing, and57 denotes a coil spring for applying an axial load. Numeral 58 denotesa part of a chamber wall of a vacuum chamber, and in this figure of thechamber wall, the left-hand side is vacuum, and the right-hand side isthe atmosphere. The test bearing 50 is a bearing number of SE608 (8 indiameter×22 in diameter×7) in both the example and the comparativeexample, in which the inner and outer races and the rotating body (ball)are SUS440C of the JIS, and the retainer (wave type) is SUS304 of theJIS. The surface roughness of the tracks of the inner and outer races is0.1Z, and the surface roughness of the rotating body is 0.05a.

The test conditions are as follows:

Rotation rate: 200 rpm

Load: axial load (50 N)

Atmosphere: in clean bench (Class 10) in the atmosphere vacuum (2.6×10⁴Pa or less)

Environmental temperature: room temperature

Measurement condition: number of dust particles having a particlediameter of 0.1 μm or more

A-(1) In the dust generation test, the total amount of dusts generatedduring the first 50 hours of the rotation was measured with themeasurement atmosphere being the atmospheric air, the environmentaltemperature being room temperature, and the axial load being 50 N. Themeasurement was conducted for dust particles having a particle diameterof 0.1 μm or more. The result was 30 for Comparative Example A, and 10for Example A, and thus Example A is excellent in comparison toComparative Example A.

A-(2) In the ion contamination performance test, the anion amountgenerated from the rolling bearing was measured. As a result, as shownin the graph of FIG. 5, the amount of the anion generated in Example Ais smaller than that in Comparative Example A.

A-(3) In the out gas performance test, as shown in the graph of FIG. 6,under the pressure of from the atmospheric pressure to 1×10⁻⁶ Pa, thetemperature, at which a gas is generated, was measure with graduallyincreasing the atmospheric temperature. As a result, in ComparativeExample A, a gas is generated at a level of room temperature and apressure of 1×10⁻¹ Pa, whereas in Example A, no gas is generated evenwhen the pressure is lowered to 1×10⁻⁴ Pa.

A-(4) With respect to the torque characteristics, the spike noise is0.072 gfcm in Example A, whereas the spike noise is 0.156 gfcm inComparative Example A, and thus that in Example A is reduced by half incomparison to Comparative Example A. With respect to noisecharacteristics, i.e., sound (axial vibration value), it is 38.8 mG inExample A, whereas it is 44.6 mG in Comparative Example A, and thusExample A is good in comparison to Comparative Example A.

A-(5) With respect to the change in torque after allowing stand at roomtemperature, as shown in the graph of FIG. 8, no change was found afterallowing stand for 1 month or more in comparison to the valueimmediately after aging.

(B) Film 27 in Solid State comprising Fluorine-containing PolyurethanePolymer Compound

The case where the film 27 in a solid state comprising thefluorine-containing polyurethane polymer compound is formed on the outerperipheral surface of the inner race 22, the inner peripheral surface ofthe outer race 23, the surface of the rotating body 24, and the surfaceof the retainer 25 is described. The film 27 also may be formed at leaston the race surfaces of the inner and outer races 22 and 23.

The film 27 has a three-dimensional network structure comprising a unitshown by the general formula —C_(x)F_(2x)—O— (X is an integer of from 1to 4) as the main structural unit, in which the average molecular weightis several millions, and the molecules are bonded to each other with anurethane bond. The three-dimensional network structure is an expressionof chemical structure, and it does not mean that the cross section ofthe film is of network, but means that the molecules are continuouslyconnected to form network to form a uniform structure packed densely.Such a fluorine-containing polyurethane polymer compound may be formedby changing the chemical structure by using a fluorine-containingpolymer having a functional group with the ends being an isocyanateshown in the following chemical formula 4. As the fluorine-containingpolymer having a functional group with the ends being an isocyanate, aderivative of perfluoropolyether (PFPE), specifically FONBLIN ZDerivative (FONBLIN Z DISOC, etc.), a trade name, of Montecatini Inc.,is preferably used.

An example of a method for forming the film 27 of thefluorine-containing polyurethane polymer compound described above isthen described.

(B-a) Attaching Treatment

A solution for obtaining the film 27 comprising the fluorine-containingpolyurethane polymer compound is prepared, and the inner and outer races22 and 23, the rotating body 24 and the retainer 25 are individuallyimmersed in the solution, or the bearing 16 in the state obtained byfabricating them is immersed and rotating in a few times, so as toattach a film in a liquid state to the inner race 22, the outer race 23,the rotating body 24 and the retainer 25.

In the case of locally attaching, it is immersed after masking theunnecessary part, or the solution is sprayed.

Furthermore, the solution may be injected in the position between theinner and outer races 22 and 23, at which the rotating body 24 ispresent, by a dropping pipette or the like.

The solution prepared herein is obtained by diluting, for example, thefluorine-containing polymer having a functional group with the endsbeing an isocyanate (FONBLIN Z Derivative (FONBLIN Z DISOC) with asuitable dilution solvent (fluorine series solvent SV90) to aconcentration the fluorine-containing polymer of 1 mass %.

(B-b) Drying Treatment

The whole of the rolling bearing 16, to which the liquid state film isattached, is heated to from 40 to 50° C. for about 1 minute to removethe solvent contained in the liquid state film.

In this stage, it is still a liquid film having fluidity.

(B-c) Hardening Treatment

Thereafter, it is heated to from 100 to 200° C. for 20 hours.

Accordingly, the chemical structure of the liquid film is changed tooccur the hardening reaction, and a film 27 of the fluorine-containingpolyurethane polymer compound is obtained. Incidentally, in thishardening treatment, the isocyanate (NCO) at the end of the individualfluorine-containing polymer having a functional group disappears by thefour kinds of hardening reactions shown in the following chemicalformulae 5 to 8, and the three-dimensional network structure is formedby bonding the respective fluorine-containing polymers having afunctional group with urethane bonds. By the urethane bond, linearcrosslinking schematically shown in FIG. 9A is formed by the hardeningreactions shown in the chemical formulae 5 and 6, and three-dimensionalcrosslinking schematically shown in FIG. 9B is formed by the hardeningreactions shown in the chemical formulae 7 and 8. In FIG. 9, thechemical formula 4 is schematically expressed with simplification asshown in the following chemical formulae 9.

According to the procedures, in the constitutional elements of therolling bearing 16, the film 27 can be formed at the parts that are incontact with each other to a suitable thickness. The attaching treatment(B-a) and the drying treatment (B-b) may be repeated several timesdepending on necessity, and finally the film thickness of the film 27 isset at, for example, from 0.1 to 3 μm. However, the property of thesolution used, the method for forming the thin film, the film thicknessafter formation and the like may be appropriately set.

The properties of the state, in which the solution prepared in theattaching treatment (B-a) is only concentrated and dried (the statehaving fluidity), and the state, in which the solution prepared in theattaching treatment (B-a) is attached to a stainless steel plate or thelike and then hardened, are analyzed and described.

The former is analyzed by the FT-IR method (the Fourier transformationinfrared spectroscopy, the liquid membrane method). As a result, asshown in the graph of FIG. 10 (examples of a thin film and a thick filmare shown, respectively), peaks of NH (3,300 cm⁻¹), N═C═O (2,279 cm⁻¹),N(H)C═O (1,712 cm⁻¹ 1,546 cm⁻¹), benzene (1,600 cm⁻¹) and the like arefound in addition to the peaks of the fluorine series, and it isconfirmed that a benzene ring, an urethane bond and an isocyanate arepresent as a functional group. While the thin film and the thick filmare respectively measured herein, the analysis can be conductedirrespective to the film thickness. The later is analyzed by the FT-IRmethod (the Fourier transformation infrared spectroscopy, the highsensitivity reflection method). As a result, as shown in the graph inFIG. 11, peaks of a benzene ring and an urethane bond are found, but apeak of an isocyanate is not found. That is, the change in chemicalstructure of the functional group by the hardening reactions shown bythe chemical formulae 5 to 8 shown above is confirmed.

Because the film 27 described above has a three-dimensional networkstructure by itself to be densely coated on an article to be coated, andhas a lubricating property by itself, generation of dusts such as wearand peeling can be suppressed to avoid direct contact of theconstitutional elements of the bearing, and the friction resistancebecomes extremely small, so that the rotating and sliding operationbecomes smooth. Furthermore, the film 27 does not contain a thickenerhaving non-uniform particle diameters and an ion for uniform dispersionof the thickener as in the conventional fluorine based grease.

Accordingly, the torque characteristics is stabilized, for example, theoperation of the rolling bearing 16 for supporting therecording/reproduction head 4 becomes extremely smooth, so as not toform a minute spike noise, which has been conventionally observed, andas a result, the positional accuracy of the recording/reproduction head4 is improved. Even when the dust component generated from the film 27is caught by the protective film of the disk 2 for recordinginformation, because the protective film and the dust component from thefilm 27 have the same component, it does not become obstruction ofrecording/reproduction.

Incidentally, as another example of the invention, the film 27 describedin the examples described above may have a structure, in which afluorine-containing polymer such as fluoropolyether is added anddispersed in a fluidized state into the three-dimensional networkstructure formed by bonding the molecules by an urethane bond. In thiscase, specifically, the solution prepared in the attaching treatment(B-a) in the forming method in the example describe above is changed toone obtained by mixing a fluorine-containing polymer having a functionalgroup with the ends being an isocyanate (for example, FONBLIN ZDerivative, a trade name (FONBLIN Z DISOC, etc.)) and afluorine-containing polymer containing no functional group as thefluorine-containing compound (for example, FONBLIN Z Derivative, a tradename (FONBLIN Z-60, etc.)) in a prescribed ratio. In this case, becausethe fluorine-containing polymer having no functional group is not bondedto the fluorine-containing polymer having a functional group in thehardening treatment (B-c), it becomes fluidized inside the film 27 toexhibit a lubricating function by oozing from the surface. Thefluorine-containing polymer is not limited to the fluorine-containingpolymer having no functional group described above, but may be thefluorine-containing polymers having a functional group shown in thechemical formulae 10 and 11.

The dust generation life and the torque life of the film 27 describedabove have been investigated, and are described. Two samples, Example Band Comparative Example B, are investigated herein.

In Example B, the film 27 is formed on the whole surfaces of the innerand outer races 22 and 23, the rotating body 24, and the retainer 25.The film 27 is one obtained by adding a fluorine-containing polymerhaving no functional group (FONBLIN Z Derivative (FONBLIN Z-60) to afluorine-containing polymer having a functional group with the endsbeing an isocyanate (FONBLIN Z Derivative (FONBLIN Z DISOC), in whichthe concentration of the FONBLIN Z Derivative (FONBLIN Z DISOC) is 1mass %, and the concentration of the FONBLIN Z Derivative (FONBLIN Z-60)is 0.25 mass %.

In Comparative Example B, DEMNUM, a trade name, produced by DaikinIndustries, Ltd. is used as a fluorine based grease, which is sealed inthe rolling bearing 16.

For the test in an atmospheric environment, the equipment shown in FIG.3 is used, and for the test in a vacuum environment, the equipment shownin FIG. 4 is used.

As the test bearing 50, the same one in the case of Example A andComparative Example A of the film 27 comprising the fluorine-containingpolymer is used in both Example B and Comparative Example B.

The test conditions for the rotation rate, the load, the atmosphere andthe environmental temperature are also the same as the case of the film27 comprising the fluorine-containing polymer.

The measurement conditions are also the same as the case of the film 27comprising the fluorine-containing polymer.

B-(1) In the dust generation test, as similar to the case of the film 27comprising the fluorine-containing polymer, the total amount of dustsgenerated during the first 50 hours of the rotation was measured withthe measurement atmosphere being the atmospheric air, the environmentaltemperature being room temperature, and the axial load being 50 N. Themeasurement was conducted for dust particles having a particle diameterof 0.1 μm or more. The result was 30 for Comparative Example B, and 10for Example B, and thus Example B is excellent in comparison toComparative Example B.

That is, because the film 28 of Example B is a uniform film of athree-dimensional network structure densely packed, peeling and wear aredifficult to occur on rotating and sliding of the constitutionalelements of the rolling bearing 16.

B-(2) In the torque life test, the atmosphere is vacuum, theenvironmental temperature is room temperature, and the axial load is 25N or 50 N. Example B and Comparative Example B are measured herein. Asshown in the graph of FIG. 7, in Example B, while the measurement isterminated at 600 hours, it can be reduced in that the torque is from3×10⁻³ to 4×10⁻³ N·m for an axial load of 25 N, and the torque is from5×10⁻³ to 6×10⁻³ N·m for an axial load of 50N, but in ComparativeExample B, the torque is from 9×10⁻³ N·m for an axial load of 25 N, andthe torque is from 11×10⁻³ N·m for an axial load of 50N. As shownherein, the torque of Example B can be certainly reduced to about halfof Comparative Example B.

In the case where the atmosphere is vacuum, the environmentaltemperature is a high temperature (200° C.), and the axial load is 50 N,as shown in FIG. 12 (in which the ordinate shows the torque, and theabscissa shows the rotation time), the torque becomes extremely large at10 hours in Comparative Example B, whereas in Example B, no problemoccurs after 90 hours. Accordingly, the torque life reveals theremarkably excellent result in comparison to Comparative Example Birrespective to the ups and downs of the atmospheric temperature.

Accordingly, it is considered that because the component added to thebase component is not bonded thereto, the component added has fluidityto exhibit a lubricating function, and it contributes to the reductionin torque.

As the film 27, in addition to those described above, one obtained byusing the fluorine-containing polymer having a functional group with theends being an isocyanate (FONBLIN Z Derivative (FONBLIN Z DISOC), inwhich the concentration is 1 mass %,

one obtained by adding a fluorine-containing polymer having a functionalgroup with the ends being a hydroxyl group (—OH) (FONBLIN Z Derivative(FONBLIN Z DOL) to a fluorine-containing polymer having a functionalgroup with the ends being an isocyanate (FONBLIN Z Derivative (FONBLIN ZDISOC), in which the concentration of the FONBLIN Z Derivative (FONBLINZ DISOC) is 1 mass %, and the concentration of the FONBLIN Z Derivative(FONBLIN Z DOL) is 0.25 mass %, and

one obtained by adding a fluorine-containing polymer having a functionalgroup with the ends being a hydroxyl group (—OH) (FONBLIN Z Derivative(FONBLIN Z DOL) and a fluorine-containing polymer having no functionalgroup (FONBLIN Z Derivative (FONBLIN Z-60) to a fluorine-containingpolymer having a functional group with the ends being an isocyanate(FONBLIN Z Derivative (FONBLIN Z DISOC), in which the concentration ofthe FONBLIN Z Derivative (FONBLIN Z DISOC) is 1 mass %, and the totalconcentration of the FONBLIN Z Derivative (FONBLIN Z DOL) and theFONBLIN Z Derivative (FONBLIN Z-60) is 0.25 mass % may be used.

The invention is not limited to the embodiments described above, butvarious applications and modifications may be considered.

(1) The information equipment of the invention maybe, in addition to thehard disk drive device described above, a device having a precisionrotating mechanism.

(2) While a deep groove ball bearing is used as the rolling bearing 16for supporting the swing arm of the movement unit 5 in the embodimentsdescribed above, other various rolling bearings may be used.

(3) While the film 27 is formed in the rolling bearing 16 for supportingthe swing arm of the movement unit 5 in the embodiments described above,the film 27 may also be formed in the rolling bearing 7 of the spindleunit 3 in the similar manner. In this case, it can contribute to theimprovement in rotation precision of the disk 2 for recordinginformation.

(4) In the hardening treatment (B-c) in the embodiments described above,an energy of an electromagnetic wave (light), such as an ultravioletray, an infrared ray, a γ-ray, an electron beam and the like, may beused instead of the heating. The drying treatment (B-b) may be omitted.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. An information equipment comprising: a rockingmechanism for rocking an element of said equipment, and a rollingbearing for supporting said rocking mechanism, wherein said rollingbearing has, on at least a race surface thereof, a film comprising afluorine-containing polymer having a functional group formed under astate having fluidity, and a thickness thereof is set at 0.2 μm or less;and wherein recording/reproduction of information is conducted to a diskfor recording information having, on a surface thereof, a protectivefilm of the same composition of said film.
 2. An information equipmentdescribed in claim 1, wherein said rolling bearing has said film formedat least one race surfaces of an inner race and an outer race.
 3. Aninformation equipment described in claim 1, wherein said functionalgroup has high affinity to a metal.
 4. An information equipmentdescribed in claim 1, wherein said fluorine-containing polymer is afluoropolyether polymer.
 5. An information equipment described in claim1, wherein said fluorine-containing polymer is a polyfluoroalkylpolymer.
 6. An information equipment comprising: a rotating mechanismfor rotating an element of said equipment, and a rolling bearing forsupporting said rotating mechanism, wherein said rolling bearing has, onat least a race surface thereof, a film comprising a fluorine-containingpolymer having a functional group formed under a state having fluidity,and a thickness thereof is set at 0.2 μm or less; and whereinrecording/reproduction of information is conducted to a disk forrecording information having, on a surface thereof, a protective film ofthe same composition of said film.
 7. An information equipmentcomprising a head for recording/reproduction for conductingrecording/reproduction of information to a disk for recordinginformation, a rocking mechanism for moving said head by rocking, and arolling/bearing for supporting said rocking mechanism, wherein saidrolling bearing has, on at least on a race surface thereof, a film, ofthe same composition as a protective film on a surface of said disk forrecording information, formed under a solid state, and said filmcomprises a fluorine-containing polymer having a functional group, and afilm thickness thereof is set at 0.2 μm or less.
 8. An informationequipment comprising: a rocking mechanism for rocking an element of saidequipment, and a rolling bearing for supporting said rocking mechanism,wherein said rolling bearing has, on at least a race surface thereof, asolid film comprising a fluorine-containing polyurethane polymercompound; and wherein recording/reproduction of information is conductedto a disk for recording information having, on a surface thereof, aprotective film of the same composition of the said solid film.
 9. Aninformation equipment described in claim 8, wherein said rolling bearinghas said film formed at least one race surfaces of an inner race and anouter race.
 10. An information equipment described in claim 8, whereinsaid fluorine-containing polyurethane polymer compound has athree-dimensional network structure.
 11. An information equipmentdescribed in claim 8, wherein a fluorine-containing polymer compoundhaving fluidity is added to said fluorine-containing polyurethanepolymer.
 12. An information equipment comprising: a rotating mechanismfor rotating an element of said equipment, and a rolling bearing forsupporting said rotating mechanism, wherein said rolling bearing has, onat least a race surface thereof, a solid film comprising afluorine-containing polyurethane polymer compound; and whereinrecording/reproduction of information is conducted to a disk forrecording information having, on a surface thereof; a protective film ofthe same composite of said solid film.
 13. An information equipmentcomprising a head for recording/reproduction for conductingrecording/reproduction of information to a disk for recordinginformation, a rocking mechanism for moving said head by rocking, and arolling bearing for supporting said rocking mechanism, wherein saidrolling bearing has, on at least on a race surface thereof, a film of,the same composition as a protective film on a surface of said disk forrecording information, formed under a solid state, and